Mechanical properties and biological durability in soil contact of chemically modified wood treated in an open or in a closed system using glycerol/maleic anhydride systems

This paper presents mechanical properties and biological durability properties against soft-rot (soil bed test) and subterranean termites (grave-yard test) of the wood modified with a vinylic derivative of glycerol or polyglycerol and maleic anhydride at different curing conditions. Wood modification was performed through impregnation of European beech (Fagus sylvatica) with an aqueous solution of polyglycerol maleate, glycerol maleate, or maleic anhydride at 10 or 20% w/w concentration, followed with curing under oven heating (OHT) in an open system (120 degrees C, 150 degrees C, or 220 degrees C) or under heat pressurised steam (HPS) at 150 degrees C in a closed system. Results revealed that almost all modified wood presented higher modulus of elasticity (MOE) values than untreated wood, however, modulus of rupture (MOR) and work to maximum load in bending (WMLB) decreased considerably. Biological durability in the soil bed test against soft-rot indicated that almost all modified wood was specified as durable to very durable. However, among the treatments, the wood modified with polyglycerol maleate/glycerol maleate/maleic anhydride at 20% under OHT 150 degrees C or the wood modified at lower additive concentration (10%) under OHT 220 degrees C presented excellent durability against subterranean termites within a period of 328 days in the field.

Automated summary

This paper investigates the mechanical and biological durability properties of wood modified with vinylic derivatives of glycerol or polyglycerol and maleic anhydride under different curing conditions. While the modified wood generally showed higher modulus of elasticity values, there was a decrease in modulus of rupture and work to maximum load in bending. The modified wood demonstrated good durability against soft-rot and subterranean termites in field tests, especially those treated with polyglycerol maleate/glycerol maleate/maleic anhydride at 20% under OHT 150 degrees C or at 10% under OHT 220 degrees C.